1. Field of the Invention
The present invention relates to a light emitting diode package and, more particularly, to a light emitting diode package, which efficiently utilize the light emitted from a side of a light emitting diode chip, thereby achieving improved luminance.
2. Description of the Related Art
In general, a light emitting diode (hereinafter, referred to as ‘LED’) has advantages such as a superior monochromatic peak wavelength, environmental friendliness and suitability for miniaturization, and thus extensively used for various display devices and light sources. A typical LED package has a structure in which an LED is protected by a transparent resin encapsulant. LED devices have various structures but usually the light emitted in sideward directions from the LED, not in the forward direction, accounts for a considerable portion of light.
To utilize the sideward light, a reflective plate with a highly reflective metal film coated thereon is used. A conventional example using such a reflective plate is shown in FIG. 1. Referring to FIG. 1, the LED package 10 includes a package body 11 and an LED chip 15. The package body 11 is composed of a package substrate 11a and a reflective plate 11b, and the LED chip 15 is mounted in an inner space provided by the reflective plate 11b and encapsulated by a resin encapsulant 13. A highly reflective metal film 12 is coated on a surface of the cup-shaped reflective plate 11b so that the light emitted sideward from the LED chip 15 is reflected by the reflective plate 11b to propagate in the emission direction (upward).
In order to obtain good light efficiency, the reflective plate 11b should be installed at an appropriate angle, which requires a sufficient space. However, the LED products used for light sources of mobile phones, etc. lack spaces for installing the reflective plate at an appropriate angle due to the stringent limitation on their thickness. Also, the light loss incurred at the surface of the reflective plate is not negligible.
In order to remedy such problems, there has been suggested using a resin reflective cup with oxidation powder of a high refractive index dispersed therein instead of using the metal-coated reflective plate. FIG. 2 is a side sectional view illustrating such a conventional LED package. Referring to FIG. 2, the LED package 10′ includes a package body 11a′ and 11b′ with oxide powder of a high refractive index such as TiO2 dispersed therein. The package body 11a′ and 11b′ is composed of a package substrate 11a′ and a reflective cup 11b′ connected integrally thereto. Due to the oxide (TiO2, etc.) powder of high reflectivity and a high refractive index dispersed in the material of the reflective cup 11b′, a portion of the light incident into the reflective cup 11b′ (especially, the sideward light) is reflected upward.
However, the conventional LED package is limited in utilization since it does not have a high reflection ratio of the sideward light by the resin reflective cup 11b′, incurring a considerable amount of light loss at the resin reflective cup 11′ and resulting in a non-uniform reflection. Furthermore, due to the recent trend of miniaturized and slimmer products, the LED package does not satisfy a thickness sufficient for reflecting light, thus incurring a considerable amount of light loss through the surface of the reflecting cup 11b′. 